Erythropoietin induction in Hep3B cells is not affected by inhibition of heme biosynthesis

AbstractErythropoietin (Epo) is one of the physiologically important genes whose transcription is up-regulated by hypoxia. Our laboratory previously proposed that the sensor of this event is a heme protein which turns over rapidly. We have investigated the effects of four inhibitors of heme synthesis (4,6-dioxoheptanoic acid (DHA), isoniazid (INH), N-methyl protoporphyrin IX (MPP), and deferoxamine mesylate (DSF)) on hypoxia-, cobalt-, and DSF-induced erythropoietin (Epo) mRNA expression, heme biosynthesis, and cell viability in Hep3B cells. DHA (0.1–1.0 mM) inhibited heme biosynthesis more than 85%, but did not suppress Epo mRNA expression. Epo mRNA expression was inhibited only at higher concentrations of DHA (2, 4 mM) which also inhibited cell viability. No suppression of Epo mRNA expression by INH was observed at doses known to inhibit heme biosynthesis. MPP did not suppress Epo mRNA expression although it showed an inhibitory effect on heme biosynthesis without any decreased cell viability. 130 μM DSF, a dose which inhibited heme biosynthesis without cell toxicity, suppressed hypoxia-induced Epo mRNA expression, but enhanced cobalt-induced Epo mRNA expression. These results show that although the oxygen sensor is probably a heme protein it does not turn over rapidly. Therefore, cobalt is unlikely to act by substituting for heme iron

A new scheme to realize crosstalk-free permutations in optical MINs with vertical stacking

©2002 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Vertical stacking is an alternative for constructing nonblocking multistage interconnection networks (MINs). In this paper, we study the crosstalk-free permutation in rearrangeable, self-routing Banyan-type optical MINs built on vertical stacking and propose a new scheme for realizing permutations in this class of optical MINs crosstalk-free. The basic idea of the new scheme is to classify permutations into permutation classes such that all permutations in one class share the same crosstalk-free decomposition pattern. By running the Euler-Split based crosstalk-free decomposition only once for a permutation class and applying the obtained crosstalk-free decomposition pattern to all permutations in the class, crosstalk-free decomposition of permutations can be realized in a more efficient way. We show that the number of permutations in a permutation class is huge, enabling the average time complexity of the new scheme to realize a crosstalk-free permutation in an N by N network to be reduced to O(N) from previously O(NlogN).Xiaohong Jiang, Hong Shen, Md. Mamun-ur-Rashid Khandker, Susumu Horiguch

Exact location of the multicritical point for finite-dimensional spin glasses: A conjecture

We present a conjecture on the exact location of the multicritical point in the phase diagram of spin glass models in finite dimensions. By generalizing our previous work, we combine duality and gauge symmetry for replicated random systems to derive formulas which make it possible to understand all the relevant available numerical results in a unified way. The method applies to non-self-dual lattices as well as to self dual cases, in the former case of which we derive a relation for a pair of values of multicritical points for mutually dual lattices. The examples include the +-J and Gaussian Ising spin glasses on the square, hexagonal and triangular lattices, the Potts and Z_q models with chiral randomness on these lattices, and the three-dimensional +-J Ising spin glass and the random plaquette gauge model.Comment: 27 pages, 3 figure

Blocking behaviors of crosstalk-free optical Banyan networks on vertical stacking

Banyan networks are attractive for constructing directional coupler (DC)-based optical switching networks for their small depth and self-routing capability. Crosstalk between optical signals passing through the same DC is an intrinsic drawback in DC-based optical networks. Vertical stacking of multiple copies of an optical banyan network is a novel scheme for building nonblocking (crosstalk-free) optical switching networks. The resulting network, namely vertically stacked optical banyan (VSOB) network, preserves all the properties of the banyan network, but increases the hardware cost significantly. Though much work has been done for determining the minimum number of stacked copies (planes) required for a nonblocking VSOB network, little is known on analyzing the blocking probabilities of VSOB networks that do not meet the nonblocking condition (i.e., with fewer stacked copies than required by the nonblocking condition). In this paper, we analyze the blocking probabilities of VSOB networks and develop their upper and lower bounds with respect to the number of planes in the networks. These bounds depict accurately the overall blocking behaviors of VSOB networks and agree with the conditions of strictly nonblocking and rearrangeably nonblocking VSOB networks respectively. Extensive simulation on a network simulator with both random routing and packing strategy has shown that the blocking probabilities of both strategies fall nicely within our bounds, and the blocking probability of packing strategy actually matches the lower bound. The proposed bounds are significant because they reveal the inherent relationships between blocking probability and network hardware cost in terms of the number of planes, and provide network developers a quantitative guidance to trade blocking probability for hardware cost. In particular, our bounds provide network designers an effective tool to estimate the minimum and maximum blocking probabilities of VSOB networks in which different routing strategies may be applied. An interesting conclusion drawn from our work that has practical applications is that the hardware cost of a VSOB network can be reduced dramatically if a predictable and almost negligible nonzero blocking probability is allowed.Xiaohong Jiang; Hong Shen; Khandker, Md.M.-ur-R.; Horiguchi, S

Naive mean field approximation for image restoration

We attempt image restoration in the framework of the Baysian inference. Recently, it has been shown that under a certain criterion the MAP (Maximum A Posterior) estimate, which corresponds to the minimization of energy, can be outperformed by the MPM (Maximizer of the Posterior Marginals) estimate, which is equivalent to a finite-temperature decoding method. Since a lot of computational time is needed for the MPM estimate to calculate the thermal averages, the mean field method, which is a deterministic algorithm, is often utilized to avoid this difficulty. We present a statistical-mechanical analysis of naive mean field approximation in the framework of image restoration. We compare our theoretical results with those of computer simulation, and investigate the potential of naive mean field approximation.Comment: 9 pages, 11 figure

Monte Carlo Study of the Anisotropic Heisenberg Antiferromagnet on the Triangular Lattice

We report a Monte Carlo study of the classical antiferromagnetic Heisenberg model with easy axis anisotropy on the triangular lattice. Both the free energy cost for long wavelength spin waves as well as for the formation of free vortices are obtained from the spin stiffness and vorticity modulus respectively. Evidence for two distinct Kosterlitz-Thouless types of defect-mediated phase transitions at finite temperatures is presented.Comment: 8 pages, 10 figure

Critical phase of a magnetic hard hexagon model on triangular lattice

We introduce a magnetic hard hexagon model with two-body restrictions for configurations of hard hexagons and investigate its critical behavior by using Monte Carlo simulations and a finite size scaling method for discreate values of activity. It turns out that the restrictions bring about a critical phase which the usual hard hexagon model does not have. An upper and a lower critical value of the discrete activity for the critical phase of the newly proposed model are estimated as 4 and 6, respectively.Comment: 11 pages, 8 Postscript figures, uses revtex.st

Cause of cavitation instabilities in three-dimensional inducer

Alternate blade cavitation, rotating cavitation and cavitation surge in rocket turbopump inducers were simulated by a commercial CFD code. In order to clarify the cause of instabilities, the velocity disturbance caused by cavitation was obtained by subtracting the velocity vector under noncavitating condition from that under cavitating condition. It was found that there exists a disturbance flow towards the trailing edge of the tip cavity. This flow has an axial flow component towards downstream which reduces the incidence angle to the next blade. It was found that all of the cavitation instabilities start to occur when this flow starts to interact with the leading edge of the next blade. The existence of the disturbance flow was validated by experiments.http://deepblue.lib.umich.edu/bitstream/2027.42/84249/1/CAV2009-final50.pd

Low-frequency noise assessment of work function engineering cap layers in high-k gate stacks

Engineering the effective work function of scaled-down devices is commonly achieved by the implementation of capping layers in the gate stack. Typical cap layers are Al2O3 for pMOSFETs and La-oxide or Mg for nMOSFETs. Besides introducing a dipole layer at the SiO2/high-κ interface, the in-diffusion of the metal ions may lead to either passivation or generation of traps in the SiO2/high-κ layer. This paper uses low frequency noise studies to determine the impact of capping layers on the quality of the SiO2/HfO2 gate stacks. The influence on the trap profiles of different types of cap layers, different locations of the cap layer (below or on top of the HfO2 dielectric) and the impact of different thermal budgets, typically used for the fabrication of Dynamic Random Access Memory (DRAM) logic devices, are investigated. The differences between several metal oxides are outlined and discussed